This invention relates generally to devices for extracting water and other liquids from liquid impregnated materials, such as waste and pulp, and more particularly, to such a unit in the form of a vertical helical screw undergoing relative rotation with respect to a surrounding drainage screen.
The device which is the subject of this invention finds particular use with a waste disposal apparatus or system wherein upon treatment of the waste material, means must be provided for separating the solids and the liquids from within a slurry. This waste disposal system in general, may include a pulper having a tank containing the waste material, fibrous material, garbage and other disposable waste in the presence of a high percentage of water, all being subjected to the disintegrating action of a rotatable impeller having suitable material disintegrating cutters. (See commonly assigned U.S. Pat. Nos. 2,729,146; 3,164,329; 3,584,800; 3,620,460 and 3,885,745.) In apparatus of this type there is associated with the tank discharge, a means for delivering the water-laden disintegrated material to a liquid extracting device often referred to as a hydro-extractor in which a helical screw is made to undergo rotation within a cylincrical sieve. The hydro-extractor separates the solids from the liquids by withdrawing the liquid from the material received from the pulper or selected disintegrating or mascerating unit. In U.S. Pat. No. 3,394,649, having a common assignee with this application, there is disclosed such a hydro-extractor in which there is a cylindrical screen or hollow cylindrical sieve surrounding the major portion of the screw.